On Gardening

Cool and collected, old seeds fare better in the refrigerator

At Green Spring Gardens, unused seeds are filed in the fridge.
At Green Spring Gardens, unused seeds are filed in the fridge. (Adrian Higgins/the Washington Post)

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By Adrian Higgins
Thursday, March 11, 2010

Locked in a seed the size of a speck is all the mystery of the universe. Unless it is locked in a shed.

Then, one discovers, the seed is no more a miraculous and latent life force but a grain that is dead for all time. Or as any caveman will tell you, "Fridge good, shed bad."

If you are a vegetable gardener and a pack rat, as I am, you will find half-used packets of seed all over the place and dating back years. Seed pouches turn up in the pockets of an old coat, in drawers of the bedroom dresser, in the recesses of a gardening bag stored in the shed and on the pegboard behind the workbench.

Like a bookworm who cannot part with the least valuable book, no matter how bad or old, I am faced at every turn with old seed packets, reminders of years when my winter ambitions were bigger than my spring real estate. Mostly, they were packets that had been opened with great anticipation, but now contained the leftover seeds in muddied pouches. Recalling the excitement of first receiving them was nowhere near as great as the actual excitement of first receiving them.

The whole point of a seed, after all, is to look forward, not back. Nowhere was this rift more pronounced than in a monster packet of arugula seed that I bought six years ago. I don't know why, but I purchased a quarter-pound of arugula seed. That's 60,000 seeds, enough to plant a row almost half a mile long. Or enough to sit forgotten in a canvas bag for years.

With seed prices creeping up each year, no doubt because of the back-to-the-garden movement and the ensuing demand for seed, it seemed logical to see if any of this germ was still viable, and if the method of storage made a difference.

I have old catalogues (that pack rat again) and could see, for example, that over the past two years the price of tomato seeds was up 11 percent, carrot 12 percent, bean 10 percent and my favorite pumpkin, a squat red thing called Cinderella, 20 percent.

I took the old arugula and 17 other seed packets and put their contents to the basic germination test: Using a given number of seeds (I chose 20 of each), I wrapped them in moist paper towels, placed them in opened plastic bags and set them aside at room temperature.

The results contained few real surprises: Seeds that had been kept in the fridge survived, more or less, while those left elsewhere did poorly. Seeds need warm temperatures and moisture to germinate, but first they also need cool temperatures and some humidity to remain in a viable dormant state. Behold the crisper.

Here were some of my shed duds: turnips from 2004, 0 percent germination; carrots from 2004, 0 percent; rutabagas from 2007, 0 percent; that arugula, 15 percent germination.

For seeds in the fridge, the results were: tomatoes from 2007, 100 percent germination; cantaloupes from 2002, 35 percent germination; spinach from 2007, 80 percent.

The one pleasant surprise is that beet seeds and their very close relative, Swiss chard, seem to survive the rank neglect of the shed shelf, possibly because their seeds are formed and protected in enclosed clusters. Thirteen of the 20 chard seeds, dating to 2005, germinated. Sixteen of the beet seeds sprang to life, though they had been purchased in 2004.

The gardeners at Fairfax County Park Authority's Green Spring Gardens west of Alexandria are old hands at keeping alive their seed stock, and needless to say, the practice involves spare refrigerators. It is astonishing how long seed will last if you take the small effort of keeping it chilled, if not frozen. The unused seed is kept in a gray metal index card file, sorted alphabetically. Big old bean and pea seeds are stored in recycled, jumbo-size coffee cans.

Some dated back to 1999 and were still sprouting when needed. "I just seal them up and put them back for next year," said gardener Donna Stecker, having no sense of just how smug that sounded to a seed-killing scribe. All is dutifully noted, including the current year's germination rate.

"The fresher the seed, the better it is, of course," said Stecker. "One year we took everything from the 1990s, especially lettuce, and just mixed them up and put them under the pea trellising and got beautiful seed up."

I've got the message: Fridge good, shed bad. My own experiment has at least allowed me to throw out seed I now know to be poor, and that itself is a step toward liberation for a seed hog. This winter, I've bought all manner of fresh new seed, and yes, the unused portion has been dutifully wrapped, noted and placed in the cosseting chill of a modern icebox. Perhaps you can teach an old dog new tricks.


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